The kitchen light had to be on in order for the cop to have craned his neck to see Neville in the chair. It seems a tight corner in which to view from a window.
I've said this before,that the natural thing to do when looking through a window,is to look straight ahead first before looking nearside. All I can say is that the cops spatial vision must be extraordinary,as I would have said that as he looked ahead he DID see a womans' body first and then on entering,saw the body of Neville in the corner.